Abstract: An inversion spring unit for a thermal overload relay and method for making the same, comprising a support member, a spring plate having a first end, a second end, an elongated central axis, and first and second side portions disposed on opposite sides of the central axis, the side protions being bent towards each other at the first end and attached at the first end to the support member for causing the second end of the spring plate to curve in a first direction away from the central axis, and a lug disposed intermediate the first and second ends for selective engagement with a drive portion to cause the second end of the spring plate to curve in a second direction opposite the first direction.

Abstract: An inversion spring unit for a thermal overload relay and method for making the same, comprising a support member, a spring plate having a first end, a second end, an elongated central axis, and first and second side portions disposed on opposite sides of the central axis, the side portions being bent towards each other at the first end and attached at the first end to the support member for causing the second end of the spring plate to curve in a first direction away from the central axis, and a lug disposed intermediate the first and second ends for selective engagement with a drive portion to cause the second end of the spring plate to curve in a second direction opposite the first direction.

Abstract: A thermal overload relay comprising a change-over spring mechanism and a contact mechanism that is separated from the spring mechanism. The contact mechanism is actuated by the spring mechanism, which is driven by a bimetallic strip when an overcurrent flows through the strip. The spring mechanism has no electrically conducting portion. The change-over point of the spring mechanism varies only a little, thus enhancing the reliability. The spring mechanism is easy to assemble and adjust.

Abstract: A thermal-type overload relay which uses a bimetallic element for sensing overload currents includes a shifter controlled by the bimetallic element to shift a release lever to which is attached a spring. The spring controls a movable board which has two reversible stable positions corresponding respectively to turn off or on a pair of normally open contacts and a pair of normally closed contacts.The movable board is a molding of insulated material carrying a pair of spaced insulated contacts and also includes a segment which is externally visible to display an indication of which pair of contacts is open and which is closed.

Abstract: A thermal overload relay of the type which uses a shifter to transmit thermal bending of the main bimetallic element to one end of the temperature compensating bimetallic element which is connected to a release lever which controls the closing of the relay and which includes an adjusting link which has an eccentric stem whose degree of rotation controls the setting of the release lever. As a calibration control to correct for unintended manufacturing variations and aging effects, the adjusting link supports an adjustment pin with an eccentric stem which abuts the eccentric stem of the adjusting dial to provide further control of the setting of the release lever.